1. Field of Invention
This invention relates generally to processes for the reduction of ruminant animal methane emissions, specifically to a process for the utilization of ruminant animal methane emissions as a source of energy.
2. Description of the Related Art
Methane emissions from ruminant animals account for about twenty percent of total global methane emissions, and atmospheric methane accounts for about twenty percent of planetary warming. In addition to the environmentally destructive effects of ruminant animal methane emissions, such emissions represent wasted energy, as a significant percentage of the food ruminant animals eat is lost as methane. Accordingly, there have been significant efforts in the past to reduce ruminant animal methane emissions.
Ruminant animal methane emissions, or, more specifically, enteric fermentation methane emissions, originate in the four-stomach digestive tract common to all ruminant animals, which includes the rumen, a large forestomach connected to the four-stomach digestive tract. The rumen contains a host of digestive enzymes, fungi, bacterium, and protozoa, and the bulk of digestion, as well as methane production via enteric fermentation, takes place here. Not surprisingly, all prior efforts to reduce enteric fermentation methane emissions from ruminant animals, which include dairy cows, beef cattle, sheep, goats, water buffalo, and camels, have focused on modifications associated with the rumen or digestive tract.
Past modification efforts have included: vaccines designed to limit methanogenic, or methane-producing, microorganisms in the rumen or digestive tract; feed reformulations designed to alter the chemical or microbial environment of the rumen or digestive tract to limit methane production; feed reformulations designed to decrease the amount of methane-producing foods entering the rumen or digestive tract; and selective breeding aimed at encouraging the reproductive success of ruminant animals which produce relatively low amounts of methane, presumably as a result of factors associated with the rumen or digestive tract.
While most of these prior efforts have had some success in reducing enteric fermentation emissions, none has been shown to completely, or even significantly, eliminate ruminant animal methane production. Since limited success in reducing methane production concurrently limits the economic benefits of using methane-reducing vaccines, feed formulations, or selective breeding, ruminant animal owners have generally been averse or reluctant to employ these methods. Thus, as the ruminant animal population continues to grow in accord with ever-increasing worldwide demand and methane reduction efforts fail to reduce emissions in any significant way, enteric fermentation methane emissions remain a significant source of both environmental degradation and wasted energy.
Prior to the applicants' discovery, no methods were known to reduce ruminant animal methane emissions by using such methane as a source of energy in energy consumption systems maintained outside of the digestive tracts of ruminant animals. In the past, all ruminant animal methane reduction processes have focused on limiting ruminant animal methane production rather than reducing overall atmospheric emissions through a system of methane utilization. Thus, it is one feature of several embodiments of the present invention that ruminant methane emissions are reduced through the utilization of ruminant animal methane as a source of energy.
Methane-utilizing, or methanotrophic, microorganisms are well known in the microbiology art for their capacity to grow and reproduce using methane as a source of carbon and/or energy. Methanotrophic microorganisms, specifically bacteria, have even been employed to reduce ruminant animal methane emissions by being placed directly in the rumen or digestive tract of ruminant animals and subsequently limiting production at its source. They have never, though, been employed in a microbiological growth system. They have also never been employed in a microbiological growth and harvest system that reduces ruminant animal enteric fermentation methane emissions while concurrently providing a means for harvesting products of microorganism growth, such as microorganism biomass. Methods for the utilization or consumption of methane gas as a source of feedstock fuel, including fuel used for the production heat, electricity, liquid natural gas, compressed natural gas, chemicals, industrial feedstock, and a range of other goods, are well known for their capacity to use methane as a source of energy. However, none of these methods has ever been employed to reduce enteric fermentation methane by using such methane as a source of energy for the induction of methane-based processes or for the production of electricity, heat, and/or other methane-based products.
Prior to the applicants' discovery, no methods were known to utilize ruminant animal methane emissions as a source of energy. More specifically, the connection between enteric fermentation methane emissions from ruminant animals and the directed production of methane-based goods or methane-driven processes through the utilization of enteric fermentation methane as a source of carbon and/or energy had ever been made. At least two major factors likely inhibited such a connection. First, it is not a well-known fact that, under certain conditions, certain ruminant animals produce enough methane to make methane-consumption systems such as electricity, heat, or microorganism production platforms technically and/or economically feasible. Second, ruminant animal methane emissions are not considered a viable source of carbon or energy because they are considered low-volume, non-concentrated, and, thus, unusable methane emissions. While up to ninety-five percent of enteric fermentation methane emissions exit the digestive tracts of ruminant animals as exhalation, most continue to regard such emissions as components of low-volume, diffuse, unusable flatulence. No methods are known to capture and/or consolidate enteric fermentation methane emissions in a way that would convert them into a state suitable for use as a fuel stream for the production of methane-based goods or processes. Enteric fermentation methane originates as diffuse emissions, and no methods are known to convert such emissions into a usable form. For these and other reasons, ruminant animal methane emissions have never been considered as a viable source energy, and the connection between enteric fermentation methane emissions and methane-driven process and goods production has never occurred.
Mechanical ventilation systems are well known in the livestock and agricultural science art for their capacity to draw, push, or pull air through a fully or partially enclosed ruminant animal holding, feeding, or enclosure area. The main function of mechanical ventilation systems, including tunnel ventilation systems and other ventilation systems, is to provide air flow or air exchange in order to maintain or improve the health of ruminant animals in a fully or partially enclosed holding or feeding area. It is also well known in the livestock and agricultural science art that some mechanical ventilation systems, particularly tunnel ventilation systems, have the capacity to force all or some of the air inside a fully or partially enclosed ruminant animal holding or feeding area through specific vents or fans. The outflow air coming out of ventilation fans have even been forced, directed, or led into mulch, compost, and/or other platforms designed to limit or reduce outflow air odor or dust emissions. Prior to the applicants' discovery, though, such ventilation systems used in conjunction with enclosure structures had never been considered as means to enable the capture, consolidation, and utilization of ruminant animal methane emissions as a source of energy. It is one feature of several embodiments of the present invention that animal enclosure structures and/or ventilation systems are applied as means to capture, consolidate, direct, and/or convey ruminant animal methane emissions to enable the use of such emissions as a source of energy. Prior to the applicants' discovery, ventilation systems and/or enclosure structures had never been used to capture ruminant animal enteric fermentation methane emissions, nor had such emissions ever been used to grow bacteria in a bioreactor optionally equipped with means to harvest any of the microbial products associated with bioreactor activity, particularly microbial biomass. Similarly, prior to the applicants' discovery, ventilation systems and/or enclosure structures had never been used to capture enteric fermentation methane for utilization by a methane-consumption system such as a reverse-flow reactor or microturbine. The utilization of air conveyance systems to capture enteric fermentation methane for use as a source of carbon and/or energy overcomes a range of practical problems associated with a system for capturing methane emissions from the nose and/or mouth of a ruminant animal using on-animal apparatuses such as bioreactors or microturbines, including animal mobility problems and reactor size requirements for optimal methane conversion. The straightforward utilization of structures, means, and systems that are well known and/or commonly used also overcomes a range of prior emissions capture problems, including practicability, palatability, and viability. One of skill in the art will understand that currently available and other ventilation systems can be used in accordance with embodiments of the invention.
No previous methods were known to reduce ruminant animal methane emissions by using such methane as a source of energy. Consequently, ruminant animal methane emissions remain a significant source of environmental degradation.
Several embodiments of the present invention relate to a process for the utilization of the methane produced by ruminant animals through enteric fermentation as a novel source of energy.
Embodiments of the invention have several surprising and unexpected advantages over the prior art, some of which are surprising and unexpected. One or more of these advantages are present in certain preferred embodiments of the present invention. Further objects and advantages will become apparent from the ensuing description.